The present invention relates to reclosable packaging and in particular to such packaging wherein indicia are provided to indicate the first opening of the package.
In the use of plastic bags and packages, particularly for foodstuffs, it is important that the bag be hermetically sealed until the purchaser acquires the bag and its contents, takes them home, and opens the bag or package for the first time. It is then commercially attractive and useful for the consumer that the bag or package be reclosable so that its contents may be protected. Flexible plastic zippers have proven to be excellent for reclosable bags, because they may be manufactured with high-speed equipment and are reliable for repeated reuse.
A typical zipper is one which has a groove at one side of the bag mouth and a rib at the other side, which rib may interlock into the groove when the sides of the mouth of the bag are pressed together. Alternatively, a member having a plurality of ribs may be on one side of the bag mouth, while a member having a plurality of channels may be on the other side, the ribs locking into the channels when the sides of the mouth of the bag are pressed together. In such a case, there may be no difference in appearance between the two members, as the ribs may simply be the intervals between channels on a strip which may lock into another of the same kind. In general, and in short, some form of male/female interengagement is used to join the two sides of the bag mouth together. The so-called members, or strips, are bonded in some manner to the material from which the bags themselves are manufactured. Usually, pull flanges extend above the rib and groove strips, which pull flanges may be pulled apart for access to the interior of the bag.
Although flexible zippers of this variety are quite popular, they do not always prevent the inadvertent or unwelcome opening of a bag or package within the store, and various additions have been made to provide tamperevident seals which would reveal when it has been opened prior to purchase. The problem of providing a tamper-evident zipper is exacerbated in package designs wherein the zipper is provided with a slider. While a slider facilitates a consumer opening and reclosing the package and hence is desirable in some instances, the slider makes it difficult for the manufacturer to employ conventional techniques to render the package tamper evident.
It is known to provide a zipper package construction which is designed to undergo some permanent change in the package appearance when the package is opened for the first time. In particular, it is known to provide a zipper package with a tamper-evident, non-reclosable peel seal which gives a positive indication of having been broken when a package is first opened and which is non-reclosable after being first opened.
Such zipper package constructions should also have other desirable features. For example, the package should be xe2x80x9cuser friendlyxe2x80x9d in the sense that the steps necessary for the initial opening of the package prior to the use of the zipper are obvious or intuitive to the consumer. Also the zipper package design should allow the package to be formed on conventional packaging equipment with little or no modification of the equipment being required. In cases where the zipper packaging includes a slider, the tamperevident feature should be compatible with the slider. Similarly, where the package contents require hermetic sealing, it is desirable that the tamper-evident feature also permit such hermetic sealing.
The present invention is directed to a reclosable packaging having a slider/zipper assembly, a header and a tamper-evident feature which undergoes a tangible change when the slider is moved relative to the header for the first time. The tamper-evident feature comprises a layer of sticky or adhesive material placed between a surface of the header and an opposing surface of the slider, thus forming a seal. The material must have a peel strength or resistance to rupture sufficient to resist an initial movement of the slider along the zipper. If the slider is stuck or adhered to the header, this indicates that the package or bag has not been tampered with, i.e., previously opened. When sufficient force is applied, the seal can be broken, allowing the slider to move relative to the header along the zipper in the direction of opening. Once broken, the seal cannot be restored by simply returning the slider to its original position and pressing the slider against the sticky or adhesive material. Thus the slider remains in an unsealed state which is readily detectable by the consumer, thereby providing a tangible indication that the package has been previously opened.
The reclosable packaging incorporating the foregoing feature may comprise a front wall, a rear wall opposite to the front wall, a bottom wall connecting the bottom edges of the front and rear walls, and left and right side walls connecting opposing side edges of the front and rear walls and also connected to the bottom wall. However, the tamper-evident feature disclosed herein may also be used in pouches or bags having other shapes, e.g., bags with no bottom or side panels and the bottom and side edges of the front and rear walls heat sealed together; and so forth. The zipper typically comprises a pair of complementarily profiled, extruded plastic fastener strips. The first fastener strip comprises a first interlockable member having a first profile and is attached to the front wall of the packaging; the second fastener strip comprises a second interlockable member having a second profile and is attached to the rear wall of the package. The second interlockable member is interlocked with the first interlockable member for closing the top of the package. A slider is slidably positioned over the interlockable portions of the fastener strips for movement along the zipper from side to side of the package. The slider causes the profiled interlockable members to disengage when moved in the direction of the closing end of the slider, allowing access to the contents of the package, and causes the profiled interlockable members to interlock when moved in the direction of the opening end of the slider.
In accordance with one preferred embodiment of the present invention, the slider is initially, i.e., prior to the first opening, constrained by a peel seal comprising a layer of sticky or tacky material placed between the slider and the header. In accordance with another preferred embodiment, the slider is constrained by an adhesive seal comprising a layer of adhesive material. In either case, the seal must be removed or ruptured or delaminated to permit movement of the slider relative to the header and thus provide access to the package contents. As long as the seal is intact, the consumer is assured that the slider has not been previously moved or slid along the zipper. Only during the initial access to the package contents, when the slider is moved relative to the header for the first time, will the integrity of the seal be disrupted. The broken seal produces tangible evidence that the package has been previously opened.
In accordance with a first preferred embodiment of the invention, the header to which the slider is tacked is integrally formed as an extension of the rear wall of the package or bag.
In accordance with a second preferred embodiment of the invention, the header to which the slider is tacked is integrally formed as an extension of the flange of one of the fastener strips.
In accordance with a third preferred embodiment of the invention, the header to which the slider is tacked is formed as a separate piece which is heat sealed or welded to either the rear wall of the package or bag or to the flange of one of the fastener strips.
In accordance with another preferred embodiment of the invention, the tacked slider combinations are further combined with features that provide a hermetically sealed package.
A person skilled in the art will readily appreciate that, instead of applying a layer of sticky or adhesive material on the header or slider, a strip bearing a layer of sticky or adhesive material can be heat sealed or welded to the header or slider.
In each of the above cases, a step that must be taken before the initial opening of the package results in a physical altering of the sealed package which may readily be observed or discovered by a consumer.
Other aspects of the invention are disclosed and claimed below.